An evapotranspiration model for sparsely vegetated canopies under partial root-zone irrigation

An evapotranspiration (E-T) model for sparsely vegetated canopies under partial root-zone irrigation (PRI) was developed and tested using measurements from a vineyard in the and region of northwest China. This model (PRI-ET) was mainly based on the Shuttleworth-Wallace (S-W) model and took into consideration the differences in soil water content between furrow-irrigation ditch and ridge under the PRI scheme and variable canopy shading over the surface. Estimates of E-T and its components (plant transpiration and soil evaporation) by the PRI-ET and S-W models were compared to E-T plant transpiration and soil evaporation measured by Bowen ratio-energy balance, heat-pulse sap flow sensor and micro-lysimeter, respectively. The PRI-ET model can estimate the vineyard E-T and its components more accurately than the S-W model, indicating that the PRI-ET model is suitable for estimating vineyard E-T under PRI. (C) 2009 Elsevier B.V. All rights reserved.